Environmental concerns

• disposing of waste polymers:

  • polymers are readily available, cheap to purchase and more convenient or throwaway society than alts such as glass bottles, metal dustbins, paper bags and cardboard packaging
  • lack of reactivity that makes polymers useful for storing food and chemicals safely also presents a challenge in their disposal
  • many alkene-based polymers are non-biodegradable
  • growing amount of polymer waste has serious environ effects - e.g. killing marine life
• Recycling:

  • reduces their environ impact by conserving finite fossil fuels as well as decreasing the amount of waste going to landfill
  • discarded polymers have to be stored by type
  • recycling process undermined if polymers are mixed as this renders the product unusable
  • once sorted, polymers are chopped into flakes, washed, dried and melted
  • recycled polymer is cut into pellets and used by manufacturers to make new products
• PVC recycling:

  • disposal and recycling of PVC is hazardous due to high chlorine content and range of additives present in the polymer
  • dumping PVC in landfill is not sustainable and, when burnt, PVC releases hydrogen chloride, corrosive gas and other pollutants like toxic dioxins
  • previously, recycling involved grinding PVC and reusing it to manufacture new products
  • new tech uses solvents to dissolve the polymer
  • high-grade PVC is then recovered by precipitation from the solvent and solvent is used again
• using waste polymers as fuel:

  • some polymers are difficult to recycle - derived from natural gas or petroleum, so they have a high stored energy value
  • waste polymers can be incinerated to produce heat, generating steam to drive a turbine producing electricity
  • in Sheffield and energy recovery facility incinerated non-recyclable material including waste polymers and uses the heat to generate electricity for the National Grid and to heat buildings across the city centre
• Feedstock recycling:

  • describes the chemical and thermal processes that can reclaim monomers, gases or il from waste polymers
  • the products from feedstock recycling resemble those produced from crude oil in refineries
  • these materials can be used as raw materials for the production of new polymers
  • a major advantage of feedstock recycling is that it is able to handle unsorted and unwashed polymers
• Biodegradable and photodegradable polymers:

  • bioplastics produced from plant starch, cellulose, plant oils and proteins offer a renewable and sustainable alternative to oil-based products
  • the use of bioplastics not only protects our environment but also conserves valuable oil reserves
• Biodegradable polymers:

  • broken down by microorganisms into water, CO2 and biological compounds
  • usually made from starch or cellulose or contain additives that alter the structure of traditional polymers so that microorganisms can break them down
• compostable polymers degrade and leave no visible or toxic residues

  compostable polymers based on poly(lactic acid) are becoming more common as an alternative to alkene-based polymers
• supermarket bags made from plant starch can be used as bin liners for food waste so that the waste and bad can be composed together
• compostable plates, cups and food trays made from sugar-cane fibre are replacing expanding polystyrene
• as the technology advances, bioplastics are likely to be more extensively used in packaging, electronics and more fuel-efficient and recyclable vehicles
• photodegradable polymers:

  • where the use of plant-based polymers is not possible
  • photodegradable, oil-based polymers are being developed
  • contain bonds that are weakened by absorbing light to start the degradation
  • alternatively, light-absorbing additives are used